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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script>
        var num1=10.50;
        var num2=11;
        console.log(num1);
        console.log(num2);
        console.log(Number.MAX_VALUE);
        console.log(Number.MIN_VALUE);
        console.log(Number.MAX_VALUE*2);  //   Infinity  无穷大
        console.log(-Number.MAX_VALUE*2);  // -Infinity  无穷小
        //NaN  :不是一个数字
        console.log("abc"-100);

        var result="abc"-100;
        //判断result是不是数字？如果是数字就返回true，否则返回false
        console.log(result); 
        console.log(isNaN(result));  //  true              是数字返回false 不是返回true
        var result2=200-100;
        console.log(isNaN(result2));//false
    </script>
</head>
<body>
    
</body>
</html>